@Dana240
A doorknob?! Yes, weird!
In general, I'd say, yes, just chalk it up to a business expense and move on. However 4 towels ruined is a bit excessive. How were they ruined? Stained with what? And how big was the group?
I had a towel, hand towel, and set of sheets ruined by a guest and I didn't request compensation, but I did mention it in the review. The only reason I mentioned it was because they didn't even say anything about it!
I would definitely reach out to the guest about the doorknob..."I noticed a doorknob missing after your stay. Do you know what happened to it?"
And if you don't get a reasonable response, please make sure you mention it in the review! Guests stain towels/sheets/etc. all the time and sometimes you may want to mention, sometimes not. But a missing doorknob is definitely something to mention in a review!